deadlock vs impasse

deadlock and impasse both are nouns.

Word	Noun	Adjective	Verb	Adverb
deadlock	Yes	No	No	No
impasse	Yes	No	No	No

As nouns, deadlock and impasse are synonyms defined as:

deadlock and impasse: a situation in which no progress can be made or no advancement is possible

Other synonyms of deadlock include dead end, stalemate, standstill.

deadlock (noun)	impasse (noun)
a situation in which no progress can be made or no advancement is possible	a street with only one way in or out
	a situation in which no progress can be made or no advancement is possible